A lithium ion battery is an ideal power source for a modern vehicle because of advantages of non-pollution, low cost, high capacity, long cycle of life, etc. The lithium ion battery may be formed by winding or stacking a positive plate, a separator and a negative plate sequentially to form an electric core, placing the electric core in a chamber formed by a shell and a cover plate, injecting an electrolyte in the chamber, and sealing an opening end of the shell, followed by formation. In the lithium ion battery, the cover plate is important to ensure the sealing of the shell. Whether the sealing of the shell is good may affect the safety, the aging resistance and the insulating performance of the lithium ion battery. In addition, the cover plate may account for a certain proportion of the total cost of the lithium ion battery. Production efficiency and yield of the cover plate may be enhanced to reduce the cost of the battery.
Currently, the sealing and insulation of the lithium ion battery is mainly realized by injection molding a plastic. A ceramic sealing member is also used for insulating and sealing the cover plate. The cover plate is welded with the ceramic sealing member, a positive leading-out pole and a negative leading-out pole are welded with the ceramic sealing member respectively, and the cover plate is insulated and sealed. However, the temperature at which the cover plate is welded with the ceramic sealing member is high, which may affect the material of the cover plate. Under the high temperature, the cover plate may become soft and have low strength and low production efficiency. Moreover, the cover plate is formed with various mounting members. The deformation of the cover plate may affect the performance thereof largely, especially affect the subsequent hermetical connection between the cover plate and the shell, thus increasing the difficulty of manufacturing a cover assembly to fit with the shell, reducing the yield of the battery, and affecting the practical application and the development of the battery.